System and methods for direction finding using a handheld device

ABSTRACT

A system for indicating the relative direction of a target object or location as determined from the current position of a wireless communication device. The system employs Direction of Arrival determination using an antenna array for indicating the direction of a target device and includes facilities to activate a location-indicating transmission in a target device, the ability to request that a location-indicating transmission be activated in a remote target device, relevant information reception from a target device and the display of all potential target devices within effective transmission range of the wireless communication device.

This is a Divisional Application of prior co-pending U.S. applicationSer. No. 11/357,165 filed Feb. 21, 2006, of which the entire disclosureis incorporated herein by reference.

BACKGROUND OF THE INVENTION

The present invention relates to a system for wireless direction-findingand location, and more specifically, to an automated system foridentifying target devices and relevant target device information inorder to determine a relative direction towards the target device fromthe current location of the seeking device.

DESCRIPTION OF PRIOR ART

Modern society has quickly adopted, and become reliant upon, handhelddevices for wireless communication. For example, cellular telephonescontinue to proliferate in the global marketplace due to technologicalimprovements in both the quality of the communication and thefunctionality of the devices. These wireless communication devices(WCDs) have become commonplace for both personal and business use,allowing users to transmit and receive voice, text and graphical datafrom a multitude of geographic locations. The communication networksutilized by these devices span different frequencies and cover differenttransmission distances, each having strengths desirable for variousapplications.

Cellular networks facilitate WCD communication over large geographicareas. These network technologies have commonly been divided bygenerations, starting in the late 1970s to early 1980s with firstgeneration (1G) analog cellular telephones that provided baseline voicecommunications, to modern digital cellular telephones. GSM is an exampleof a widely employed 2G digital cellular network communicating in the900 MHz—1.8 GHz band in Europe and at 1.9 GHz in the United States. Thisnetwork provides voice communication and also supports the transmissionof textual data via the Short Messaging Service (SMS). SMS allows a WCDto transmit and receive text messages of up to 160 characters, whileproviding data transfer to packet networks, ISDN and POTS users at 9.6Kbps. The Multimedia Messaging Service (MMS), an enhanced messagingsystem allowing for the transmission of sound, graphics and video filesin addition to simple text, has also become available in certaindevices. Soon emerging technologies such as Digital Video Broadcastingfor Handheld Devices (DVB-H) will make streaming digital video, andother similar content, available via direct transmission to a WCD. Whilelong-range communication networks like GSM are a well-accepted means fortransmitting and receiving data, due to cost, traffic and legislativeconcerns, these networks may not be appropriate for all dataapplications.

Short-range wireless networks provide communication solutions that avoidsome of the problems seen in large cellular networks. Bluetooth™ is anexample of a short-range wireless technology quickly gaining acceptancein the marketplace. A Bluetooth™ enabled WCD transmits and receives dataat a rate of 720 Kbps within a range of 10 meters, and may transmit upto 100 meters with additional power boosting. A user does not activelyinstigate a Bluetooth™ network. Instead, a plurality of devices withinoperating range of each other will automatically form a network groupcalled a “piconet”. Any device may promote itself to the master of thepiconet, allowing it to control data exchanges with up to seven “active”slaves and 255 “parked” slaves. Active slaves exchange data based on theclock timing of the master. Parked slaves monitor a beacon signal inorder to stay synchronized with the master, and wait for an active slotto become available. These devices continually switch between variousactive communication and power saving modes in order to transmit data toother piconet members. In addition to Bluetooth™ other popularshort-range wireless networks include WLAN (of which “Wi-Fi” localaccess points communicating in accordance with the IEEE 802.11 standard,is an example), WUSB, UWB, Bluetooth Low End Extension (BTLEE)/BluLite,ZigBee/IEEE 802.15.4, and UHF RFID. All of these wireless mediums havefeatures and advantages that make them appropriate for variousapplications.

More recently, manufacturers have also began to incorporate variousresources for providing enhanced functionality in WCDs (e.g., componentsand software for performing close-proximity wireless informationexchanges). Sensors and/or scanners may be used to read visual orelectronic information into a device. A transaction may involve a userholding their WCD in proximity to a target, aiming their WCD at anobject (e.g., to take a picture) or sweeping the device over a printedtag or document. Machine-readable technologies such as radio frequencyidentification (RFID), Infra-red (IR) communication, optical characterrecognition (OCR) and various other types of visual, electronic andmagnetic scanning are used to quickly input desired information into theWCD without the need for manual entry by a user.

Wireless communication devices employing the previously discussedcharacteristics may be used for a variety of applications other thanbasic voice communications. Exemplary applications for business mayinclude scheduling, word processing, spreadsheets, facsimiletransmission, contact management, etc. There is also a multitude ofapplications for the personal enjoyment of the user, such as games,instant messaging, display wallpaper, etc.

A wireless service provider may determine the location of a wirelesscommunication device by how it is communicating on the wireless network(e.g., by identifying the cell where a cellular phone last accessed thenetwork). While the benefit of being able to locate a communicationdevice in certain situations is apparent, such as in an emergency, theability to provide location-related information to a user would also bea great advantage. Exemplary systems now envisioned might empower a userto determine a current location using their WCD, and combined with otherapplications, may be useful for route or direction finding from acurrent location to another mapped location.

Current handheld location systems that operate with services such as theGlobal Positioning System (GPS) are now available on the market. Thesestandalone devices may provide bearings and directions to addresslocations or longitude/latitude positions. However, the bearings anddirections may only be provided relative to the moving direction of theGPS device. For stationary devices they can't be provided at all.Manufacturers have integrated these location-finding features withtraditional wireless communication devices.

However, even with the ability to determine the current position of adevice, the usefulness of these emerging navigation systems is somewhatlimited. What if the user has not yet determined their destination? Inmost status quo location systems the user must first indicate the objectof their search to the navigation system. For example, the user mustprovide a destination address for a target destination before thenavigational system may provide directional information. However, aperson in an unfamiliar area may be currently unaware of the multitudeof possible target destinations that might be of interest? What if theuser desires to find a location on a much smaller scale, such as a roomin a building that may not be established by a regional address? What ifthe destination is mobile, like the location of the closest taxi cab orpolice car in the immediate area? In an alternative application, what ifthe target is a thing (object) not a place (destination)? A person mightwant to find the current location of a set of keys, a wallet, a jacket,the wireless communication device of another user, etc. The currentlocation technologies that are integrated into wireless communicationdevices have not been envisioned to provide for these alternativesituations.

What is therefore needed is a directional and/or location finding systemthat does not require as a prerequisite a user's knowledge of what theyseek. Instead, when activated, the directional and/or location findingsystem should enable the user to manually input a desired target,manually activate (or request the activation of) a target that iscurrently inactive, as well as providing a list of potential targets toa user, which allows the user to select the target of the directionalsearch, be it either a place or object. In the case of selecting atarget from the array of discovered targets, the targets may beidentified to the user and may in some cases also provide additionalinformation relevant to the nature of the target. After a target isindicated, the user should be directed to the target through a simpleinterface that may indicate both the present user location and therelative direction to the target from this location.

SUMMARY OF INVENTION

The present invention includes at least a method, device, softwareprogram and system for determining the relative direction towards atarget from the current position of a wireless communication device. Thesystem includes provisions for the ability to activate alocation-indicating transmission in a target, the ability to requestthat a location-indicating transmission be activated in a target,information reception from multiple potential targets, the display oftargets in effective reception range of the seeking device, the displayof the target location and other information related to targets ineffective reception range of the seeking device, the display of relativedirection towards a selected target device and the display of thecurrent position of the seeking device.

In a first example of the present invention, the relative directiontowards a target within effective wireless transmission range of a WCDis determined. An antenna array composed of multiple antennas in a knownconfiguration is combined with (or within) the WCD to receiveposition-indicating transmission signals. These transmission signals aremeasured, and the measurements are used to perform a Direction ofArrival (DoA) calculation, which resolves the relative direction towardsthe target. The direction towards the target is then displayed to a useron the WCD.

The user may know the identity of the target. In this case, the user mayindicate a target identification via a variety of well-known inputmethods. In some cases, the position-indicating transmission may need tobe activated in the target. This depends on the type ofposition-indicating transmission device. Some targets will allow a userto activate the location beacon (position-indicating transmission)remotely via a wireless message to the target. Other location beaconswill only allow remote activation through permission by the owner orcontroller of the target. A third class of targets are always active,and therefore, do not require remote activation.

The encountered targets in effective transmission range of the WCD maybe displayed for the user. The user may select any of the displayedtargets for direction determination, and possibly to view additionalinformation about the target. The WCD may then use the previouslyindicated signal processing method to determine the relative directiontowards the target device. The WCD may also, in some cases, use thelocation of various targets to triangulate the current location of theWCD.

In addition, exemplary applications of the present invention arepresented. In at least one situation, the present invention may help todetermine the relative location of targets, or position markers, withina building structure. The position markers may indicate locations ofinterest, and information relevant to these locations. The targets andlocations of interest may include for example shops inside a shoppingmall or products in a supermarket. The WCD may also use informationprovided from various position markers to provide an estimation ofcurrent location within the building structure.

The present invention also has application to outdoor direction andlocation finding. The present invention may be employed to list variouslocations or targets in an outdoor setting, allowing a user to viewinformation pertaining to each target. The user may then choose one ofthe targets to locate, and the WCD will indicate relative direction tothe target from the user's current location. Further, the WCD may usepositional information provided from various target devices to providean estimation of current location on a global (e.g., latitude andlongitude) or regional basis (e.g., via map coordinates, addressinformation, street names, etc.).

DESCRIPTION OF DRAWINGS

The invention will be further understood from the following detaileddescription of a preferred embodiment, taken in conjunction withappended drawings, in which:

FIG. 1 discloses an exemplary short-range to long-range wirelesscommunication environment usable to describe at least one embodiment ofthe present invention.

FIG. 2 discloses a modular description of an exemplary wirelesscommunication device usable with at least one embodiment of the presentinvention.

FIG. 3 discloses an exemplary structural description of the wirelesscommunication device previously described in FIG. 2.

FIG. 4 discloses exemplary forms of location-finding and directionalsystems currently employed to determine direction and/or location.

FIG. 5 discloses an exemplary wireless communication device includingintegrated direction-finding features in the form of an antenna array inaccordance with at least one embodiment of the present invention.

FIG. 6 discloses an exemplary structural description fordirection-finding features usable for receiving a position-indicatingtransmission in accordance with at least one embodiment of the presentinvention.

FIG. 7 discloses exemplary antenna arrangements and an alternativestructural description for receiving a position-indicating transmissionin accordance with at least one embodiment of the present invention.

FIG. 8 discloses an exemplary position-indicating transmission anddifferent transmission strategies in accordance with at least oneembodiment of the present invention.

FIG. 9 discloses a process flowchart usable to operate at least oneembodiment of the present invention.

FIG. 10 discloses an exemplary application of the present inventionwherein position markers are employed to mark locations in a building.

FIG. 11 discloses an example of direction and/or position finding in abuilding in accordance with the application described in FIG. 10

FIG. 12 discloses a process flowchart for executing the exemplaryapplication of FIG. 10.

FIG. 13 discloses another exemplary application of the present inventionwherein position markers are employed to mark outdoor targets.

FIG. 14 discloses a process flowchart for executing the exemplaryapplication of FIG. 13.

FIG. 15 illustrates triangulation based on angles.

DESCRIPTION OF PREFERRED EMBODIMENT

While the invention has been described in preferred embodiments, variouschanges can be made therein without departing from the spirit and scopeof the invention, as described in the appended claims.

I. Wireless Communication Over Different Communication Networks.

A WCD may both transmit and receive information over a wide array ofwireless communication networks, each with different advantagesregarding speed, range, quality (error correction), security (encoding),etc. These characteristics will dictate the amount of information thatmay be transferred to a receiving device, and the duration of theinformation transfer. FIG. 1 includes a diagram of a WCD and how itinteracts with various types of wireless networks.

In the example pictured in FIG. 1, user 110 possesses WCD 100. Thisdevice may be anything from a basic cellular handset to a more complexdevice such as a wirelessly enabled palmtop or laptop computer. NearField Communications (NFC) 130 include various transponder-typeinteractions wherein normally only the scanning device requires its ownpower source. WCD 100 scans source 120 via short-range communications. Atransponder in source 120 may use the energy and/or clock signalcontained within the scanning signal, as in the case of RFIDcommunication, to respond with data stored in the transponder. Thesetypes of technologies usually have an effective transmission range onthe order of ten feet, and may be able to deliver stored data in amountsfrom 96 bits to over a megabit (or 125 Kbytes) relatively quickly. Thesefeatures make such technologies well suited for identification purposes,such as to receive an account number for a public transportationprovider, a key code for an automatic electronic door lock, an accountnumber for a credit or debit transaction, etc.

The transmission range between two devices may be extended if bothdevices are capable of performing powered communications. Short-rangeactive communications 140 includes applications wherein the sending andreceiving devices are both active. An exemplary situation would includeuser 110 coming within effective transmission range of a Bluetooth™,WLAN, UWB, WUSB, etc. access point. In the case of Bluetooth Low EndExtension (BTLEE)/BluLite, a network may automatically be established totransmit information to WCD 100 possessed by user 110. BTLEE/BluLite maybe used for battery-powered access points, since its power consumptionis low. A BTLEE access point may use the advertisement mode to morerapidly establish the initial connection to WCD 100. This data mayinclude information of an informative, educational or entertainingnature. The amount of information to be conveyed is unlimited, exceptthat it must all be transferred in the time when user 110 is withineffective transmission range of the access point. This duration isextremely limited if the user is, for example, strolling through ashopping mall or walking down a street. Due to the higher complexity ofthese wireless networks, additional time is also required to establishthe initial connection to WCD 100, which may be increased if there aremany devices queued for service in the area proximate to the accesspoint. The effective transmission range of these networks depends on thetechnology, and may be from some 30 ft. to over 300 ft. with additionalpower boosting.

Long-range networks 150 are used to provide virtually uninterruptedcommunication coverage for WCD 100. Land-based radio stations orsatellites are used to relay various communications transactionsworldwide. While these systems are extremely functional, the use ofthese systems is often charged on a per-minute basis to user 110, notincluding additional charges for data transfer (e.g., wireless Internetaccess). Further, the regulations covering these systems causeadditional overhead for both the users and providers, making the use ofthese systems more cumbersome.

II. Wireless Communication Device

As previously described, the present invention may be implemented usinga variety of wireless communication equipment. Therefore, it isimportant to understand the communication tools available to user 110before exploring the present invention. For example, in the case of acellular telephone or other handheld wireless devices, the integrateddata handling capabilities of the device play an important role infacilitating transactions between the transmitting and receivingdevices.

FIG. 2 discloses an exemplary modular layout for a wirelesscommunication device usable with the present invention. WCD 100 isbroken down into modules representing the functional aspects of thedevice. These functions may be performed by the various combinations ofsoftware and/or hardware components discussed below.

Control module 210 regulates the operation of the device. Inputs may bereceived from various other modules included within WCD 100. Forexample, interference sensing module 220 may use various techniquesknown in the art to sense sources of environmental interference withinthe effective transmission range of the wireless communication device.Control module 210 interprets these data inputs, and in response, mayissue control commands to the other modules in WCD 100.

Communications module 230 incorporates all of the communications aspectsof WCD 100. As shown in FIG. 2, communications module 230 may include,for example, long-range communications module 232, short-rangecommunications module 234 and machine-readable data module 236 (e.g.,for NFC). Communications module 230 utilizes at least these sub-modulesto receive a multitude of different types of communication from bothlocal and long distance sources, and to transmit data to recipientdevices within the transmission range of WCD 100. Communications module230 may be triggered by control module 210, or by control resourceslocal to the module responding to sensed messages, environmentalinfluences and/or other devices in proximity to WCD 100.

User interface module 240 includes visual, audible and tactile elementswhich allow the user 110 to receive data from, and enter data into, thedevice. The data entered by user 110 may be interpreted by controlmodule 210 to affect the behavior of WCD 100. User-inputted data mayalso be transmitted by communications module 230 to other devices withineffective transmission range. Other devices in transmission range mayalso send information to WCD 100 via communications module 230, andcontrol module 210 may cause this information to be transferred to userinterface module 240 for presentment to the user.

Applications module 250 incorporates all other hardware and/or softwareapplications on WCD 100. These applications may include sensors,interfaces, utilities, interpreters, data applications, etc., and may beinvoked by control module 210 to read information provided by thevarious modules and in turn supply information to requesting modules inWCD 100.

FIG. 3 discloses an exemplary structural layout of WCD 100 according toan embodiment of the present invention that may be used to implement thefunctionality of the modular system previously described in FIG. 2.Processor 300 controls overall device operation. As shown in FIG. 3,processor 300 is coupled to communications sections 310, 320 and 340.Processor 300 may be implemented with one or more microprocessors thatare each capable of executing software instructions stored in memory330.

Memory 330 may include random access memory (RAM), read only memory(ROM), and/or flash memory, and stores information in the form of dataand software components (also referred to herein as modules). The datastored by memory 330 may be associated with particular softwarecomponents. In addition, this data may be associated with databases,such as a bookmark database or a business database for scheduling,email, etc.

The software components stored by memory 330 include instructions thatcan be executed by processor 300. Various types of software componentsmay be stored in memory 330. For instance, memory 330 may store softwarecomponents that control the operation of communication sections 310, 320and 340. Memory 330 may also store software components including afirewall, a service guide manager, a bookmark database, user interfacemanager, and any communications utilities modules required to supportWCD 100.

Long-range communications 310 performs functions related to the exchangeof information over large geographic areas (such as cellular networks)via an antenna. These communication methods include technologies fromthe previously described 1G to 3G. In addition to basic voicecommunications (e.g., via GSM), long-range communications 310 mayoperate to establish data communications sessions, such as GeneralPacket Radio Service (GPRS) sessions and/or Universal MobileTelecommunications System (UMTS) sessions. Also, long-rangecommunications 310 may operate to transmit and receive messages, such asshort messaging service (SMS) messages and/or multimedia messagingservice (MMS) messages.

As a subset of long-range communications 310, or alternatively operatingas an independent module separately connected to processor 300 (notpictured), transmission receiver 312 allows WCD 100 to receivetransmission messages via mediums such as Digital Video Broadcast forHandheld Devices (DVB-H). These transmissions may be encoded so thatonly certain designated receiving devices may access the transmissioncontent, and may contain text, audio or video information. In at leastone example, WCD 100 may receive these transmissions and use informationcontained within the transmission signal to determine if the device ispermitted to view the received content.

Short-range communications 320 is responsible for functions involvingthe exchange of information across short-range wireless networks. Asdescribed above and depicted in FIG. 3, examples of such short-rangecommunications 320 are not limited to Bluetooth™, WLAN, UWB and WirelessUSB connections. Accordingly, short-range communications 320 performsfunctions related to the establishment of short-range connections, aswell as processing related to the transmission and reception ofinformation via such connections.

Short-range input device 340, also depicted in FIG. 3, may providefunctionality related to the short-range scanning of machine-readabledata (e.g., for NFC). For example, processor 300 may control short-rangeinput device 340 to generate RF signals for activating an RFIDtransponder, and may in turn control the reception of signals from anRFID transponder. Other short-range scanning methods for readingmachine-readable data that may be supported by the short-range inputdevice 340 are not limited to IR communications, linear and 2-D (e.g.,QR) bar code readers (including processes related to interpreting UPClabels), and optical character recognition devices for reading magnetic,UV, conductive or other types of coded data that may be provided in atag using suitable ink. In order for the short-range input device 340 toscan the aforementioned types of machine-readable data, the input devicemay include optical detectors, magnetic detectors, CCDs or other sensorsknown in the art for interpreting machine-readable information.

As further shown in FIG. 3, user interface 350 is also coupled toprocessor 300. User interface 350 facilitates the exchange ofinformation with a user. FIG. 3 shows that user interface 350 includes auser input 360 and a user output 370. User input 360 may include one ormore components that allow a user to input information. Examples of suchcomponents include keypads, touch screens, and microphones. User output370 allows a user to receive information from the device. Thus, useroutput portion 370 may include various components, such as a display,light emitting diodes (LED), tactile emitters and one or more audiospeakers. Exemplary displays include liquid crystal displays (LCDs), andother video displays.

WCD 100 may also include one or more transponders 380. This isessentially a passive device which may be programmed by processor 300with information to be delivered in response to a scan from an outsidesource. For example, an RFID scanner mounted in a entryway maycontinuously emit radio frequency waves. When a person with a devicecontaining transponder 380 walks through the door, the transponder isenergized and may respond with information identifying the device, theperson, etc. Alternatively, the scanner may be mounted in the WCD sothat it can read information from transponders in the vicinity.

Hardware corresponding to communications sections 310, 312, 320 and 340provide for the transmission and reception of signals. Accordingly,these portions may include components (e.g., electronics) that performfunctions, such as modulation, demodulation, amplification, andfiltering. These portions may be locally controlled, or controlled byprocessor 300 in accordance with software communications componentsstored in memory 330.

The elements shown in FIG. 3 may be constituted and coupled according tovarious techniques in order to produce the functionality described inFIG. 2. One such technique involves coupling separate hardwarecomponents corresponding to processor 300, communications sections 310,312 and 320, memory 330, short-range input device 340, user interface350, transponder 380, etc. through one or more bus interfaces.Alternatively, any and/or all of the individual components may bereplaced by an integrated circuit in the form of a programmable logicdevice, gate array, ASIC, multi-chip module, etc. programmed toreplicate the functions of the stand-alone devices. In addition, each ofthese components is coupled to a power source, such as a removableand/or rechargeable battery (not shown).

The user interface 350 may interact with a communications utilitiessoftware component, also contained in memory 330, which provides for theestablishment of service sessions using long-range communications 310and/or short-range communications 320. The communications utilitiescomponent may include various routines that allow the reception ofservices from remote devices according to mediums such as the WirelessApplication Medium (WAP), Hypertext Markup Language (HTML) variants likeCompact HTML (CHTML), etc.

III. Current Systems for Providing Location-Finding or DirectionalInformation.

There are some location-finding or direction-finding systems on themarket today. In FIG. 4, two examples are disclosed which may representtwo extremes in this technology area. These two technologies have beenimplemented to serve very different purposes, and as such, havedifferent strengths and weaknesses.

Global positioning systems may deliver a precise geographic location(e.g., latitude and longitude measurement) to a user. Traditionally,these systems have been mounted in vehicles, but now smaller compactversions are available that may be carried with a pedestrian. Thesesystems use satellites 400 or terrestrial radio networks 410 todetermine the location of a receiver in global coordinates, such aslongitude and latitude. The obvious advantage of these systems is theirability to determine the absolute location of a GPS device. Mostcommercial devices may figure the correct position of a person within afew meters.

However, while these systems deliver global location information, thereare some limitations to this technology. GPS is only usable outside dueto the need to receive a signal from satellite 400. Network assisted GPS(AGPS) systems also have limited indoor coverage, but the performance istypically not adequate. Precision can be intentionally limited bygovernment regulation due to security concerns regarding how a locationdevice may be maliciously used if too accurate. GPS positioning signalsare also subject to multipath (reflection) or environmentalinterference, especially in dense urban environments, which tends tocause location determining errors. In order to correct this problem,differential systems may be employed combining both satellite 400 andground based systems 410, however, these systems are more costly tooperate, the additional cost of which may be passed on to the consumers.Further, the software required to implement GPS directional systems maybe complex, requiring substantial hardware support in order to functionproperly.

On the other end of the spectrum is single antenna radio location basedonly on signal strength. Tracking device 420 may be tuned to thefrequency of one or more known signal emitters. In the simplestimplementation an omnidirectional antenna is used to find any targets inthe vicinity by receiving their signals, in order to indicate theirpresence and possibly the location of the tracking device. To improvethe accuracy, a unidirectional antenna on tracking device 420 may beused to measure the strength of each received signal, wherein thereception strength is indicated using a visual or audio method. The userphysically moves the device in a sweeping pattern and monitors thesignal strength indicator. The direction of strongest signal receptionis deemed to be the direction towards the target. RadarGolf™ is anexample of this type of devices. Also more sophisticated direction anddistance tracking devices exist, such as Bluespan® Ion-Kids®, which arebased on proprietary technology.

While this type of system is very economical to operate, it only haslimited applications. Tracking device 420 may locate only known objectsover relatively short range. The user of the device must physicallysweep the device back and forth in order to determine the targetdirection. There is no way to determine the absolute position of thetarget or tracking device 420 (e.g., there is no way to estimatelongitude and latitude of either tracker or target). In addition,depending on the technology employed, tracking device 420 is subject toelectromagnetic and environmental interference, and would not beeffective where this type of interference abounds, for example, in abuilding.

III. A Multiple Antenna Direction of Arrival Tracking System.

At least one embodiment of the present invention employs signalsreceived on multiple antennas in a Direction of Arrival (“DoA”) signalprocessing scheme in order to determine a relative direction to a targetfrom WCD 100. In this technique, the direction of arrival of theincident signal (e.g., the position-indicating transmission) is resolvedbased on the phase and possibly amplitude differences of signalsreceived by the elements of an antenna array. In the simplest method,historically known as the Bartlett Beamformer, the normalized receivedpower in each array look direction (θ) is calculated using the followingrelationship:

$\begin{matrix}{{P(\theta)} = \frac{{a^{H}(\theta)}{{Ra}(\theta)}}{L^{2}}} & (1)\end{matrix}$

Wherein in equation (1), a(θ) is a so called steering vector of thearray and R is the spatial covariance matrix of the received signal. Lis the number of elements in the antenna array. a^(H) denotes aconjugate transpose of the matrix a. The direction giving the highestpower is then assumed to be the direction of the target.

The covariance matrix R is obtained as:

R=E{x(t)x ^(H)(t)}  (2)

where x(t) is the vector of signals received from the antenna elementsas a function of time t.

The elements of the steering vector a(θ) are the output signals of thearray elements, when it receives a plane wave from direction θ. It isdefined as:

a _(n)(θ)=g _(n)(θ)·e ^(−jkr) ^(n) ^(·u) ^(r) ^((θ))  (3)

in which g_(n)(θ) is the complex radiation pattern of element n, k isthe wave number (defined as 2π/λ where λ is the wavelength at centerfrequency), r_(n) is the location vector of element n, and is the radialvector towards the incident wave direction θ. In a simple case of alinear array of identical and equally spaced elements the steeringvector simplifies to:

a(θ)=g(θ)[1e ^(−jkd cos θ) . . . e ^(−j(L−1)kd cos θ)]^(T)  (4)

in which d is the inter-element spacing of linear, equally spacedantenna elements in the array. θ is the angle between the lineconnecting the linearly located antenna elements and the incident wavedirection.

In a small handheld device the radiation patterns of the elements aretypically not identical because they are affected by the metallicchassis of the device. The elements may also be differently oriented dueto space limitations in the device. In this case, either Eq. (3) must beused, or the steering vector can also be directly measured in acalibration measurement, or it can be computed using electromagneticsimulation tools.

The DoA estimation accuracy decreases in the presence of multipathpropagation or noise. In the noisy multipath radio propagation channelthe accuracy can be increased by improving the resolution of the arraythrough increasing its size by adding more antenna elements. Inaddition, the distance between any two antenna elements in the arrayshould not exceed half a wavelength to obtain unambiguous DoA estimate.

Multipath radio propagation causes fading that can lead to rapid changesof the DoA estimates and temporary mispointings. To overcome the problemone aspect of the invention uses a tracking algorithm. It is based onkeeping a register of several DoA estimates and choosing the one withhighest average power to be selected as the actual output.

The DoA estimation algorithm calculates an azimuth power spectrum, i.e.the signal power received from azimuth directions. The trackingalgorithm extracts the maxima from the azimuth power spectrum. It keepstrack of e.g. the 5 strongest directions. If one of the newly extractedmaxima is close (e.g. within 10 degrees) to one of these directions,then the signal power and the direction is added to the trackeddirection. If not, the new direction is tracked. All the signal powervalues of the tracked directions are filtered using a forgetting curveand the DoA of each tracked direction is calculated using a weightedaverage of the extracted directions for this tracker. After each trackerupdate, tracked directions that are closer than e.g. 10 degrees aremerged and the number of tracked directions is reduced to the fivestrongest directions.

Without using this tracking algorithm, the strongest maximum would bechosen to be the DoA, which might lead to rapid changes in the estimatedDoA due to fading.

FIG. 5 discloses an exemplary WCD 100 configuration usable with thepresent invention. In addition to the elements and features alreadydisclosed in FIGS. 2 and 3, the present invention may also include anantenna array. A simplified three-dimensional transparent view of WCD100 is shown below the exemplary exterior picture of the device 100. Thetransparent three-dimensional view includes antennas A1-A6. The numberof antennas doesn't have to be six, but it can be any number larger thanone. The placement of antennas A1-A6 may be within the outer housing ofWCD 100 to form an array such as the one shown. The array may providedirectional field sensing that is interpreted into a direction fordisplay on WCD 100. Signal emitter 500 may emit a position-indicatingtransmission that is receivable via the antenna array. The placement andorientation of these antennas may allow a user to hold WCD 100 in anhorizontal orientation, wherein the display faces upward towards thesky. As will be seen, this orientation lends more naturally to a pointerdisplay indicating direction, such as in the use of a traditionalcompass when orienteering.

In another example (not shown) the antenna array and/or supportcircuitry may be housed within an outside component that may beremovably attached to WCD 100. This exterior component or attachment maybe connected when user 110 wants to determine direction or location, andits connection may automatically signal WCD 100 to enter a position ordirection finding mode. It is important to note that if the antennaarray is housed in an attachable exterior unit, that the orientation ofthe exterior unit with respect to WCD 100 would be a fixed,predetermined orientation with respect to the housing of WCD 100 inorder to establish a known orientation for the antenna array. In thisway, the antenna array will always be in the same (or a known)configuration when attached to WCD 100.

FIG. 5 also includes an example display shown on WCD 100 that isviewable by user 110. This display may be implemented in differentconfigurations depending upon the application to which it is applied. Inthis example, the display shows both a list of possible target objectsand an arrow pointer. There can be one or multiple active signalemitters 500 within one area at the same time. Multiple beacons canshare the same communications medium by using a multiple access method(code, frequency or time). The “KEYS” target object is currentlyselected. This object is also represented in FIG. 5 as by signal emitter500, which may be included as a keychain connected to a set of keys.Since the keys object is selected, the WCD 100 will attempt to definethe relative direction towards the target designated as keys. Thedisplay shows the directional arrow pointing in the direction of thekeys, and gives a relative direction measurement towards the keys of−90°. As the user moves toward the selected target, WCD 100 willcontinuously measure the signal of the target device and will update thedisplay accordingly so that the arrow and the directional measurementcontinue to indicate the relative direction toward the keys.

FIG. 6 includes a structural diagram of WCD 100. Again, WCD 100 includesany and or all of the elements and features previously disclosed inFIGS. 2 and 3. In FIG. 6, additional elements and features are includedthat may be composed of stand-alone devices, or may be emulated bycombinations of hardware and software present in WCD 100. Antennas A1-A6may be coupled to antenna control switch 610. Control switch 610multiplexes the antennas so that one receiver 620 may monitor incomingtransmissions from all of the antennas. Signals received on antennasA1-A6 determine the relative direction to a target from WCD 100. Thedirection of arrival of the incident signal (e.g., theposition-indicating transmission) is resolved based on the phase andpossibly amplitude differences of the signals received by the respectiveantennas A1-A6. Control switch 610 sequentially feeds the signal fromeach antenna to the receiver 620, where the Direction of Arrival (“DoA”)signal processing operates on the signal phase and possibly amplitudeinformation to determine a relative direction to a target from WCD 100.This information is fed to receiver 620. Depending on the technologyused in the switch, for example GaAs FETs vs. PIN diodes, the switch mayoperate at different speeds. Given present technology, it appears that a10 μs scan time for all antennas is conceivable. Fast switching time isbeneficial because it allows DoA estimation from short transmissions anddoes not set high requirements for the stationarity of the radiochannel.

In at least one embodiment of the present invention, receiver 620 is aBluetooth™ or Bluetooth Low End Extension (BTLEE) receiver, also knownas BluLite. BTLEE is an add-on extension to the Bluetooth™ command setcomposed especially for simple devices. This specialized command setallows low end devices to communicate wirelessly with a significantlylower power requirement. BTLEE may be implemented in chip form to makeBluetooth™ implementation in low end devices more economical. The use ofBTLEE may be more appropriate for the location of personal items. ABTLEE chipset may be incorporated into a keychain or into the lining ofa wallet or garment to allow locating via wireless communication, aswill be explained below. BT/BTLEE receiver 620 receives signalsmultiplexed from Antennas A1-A6 and uses this information to determinerelative direction using DoA signal processing as previously described.The receiver may also, in some cases, receive information containedwithin the position-indicating transmission. In these cases thedetermination of direction and the reception of information carriedwithin the signal may be delayed as the primary receiver 620 attempts tomultitask both information reception and DoA determination. Thissituation may be cured by the further example disclosed in FIG. 7.

The example structural configuration of FIG. 7 separates theresponsibility of determining DoA determination and BTLEE reception intotwo separate receiving modules. Antenna A1 is directly tied to BTLEEreceiver 720 so that information may be received real-time from theposition-indication transmission for immediate decoding. As will bediscussed later, this information may include identification informationannouncing that the device is a possible target, identification of thetarget and other target related data. Dedicated DoA receiver 730 maythen be free to concentrate on deriving the time and spacingrelationship between the reception of the position-indicatingtransmission at the various antennas in the antenna array, which is usedto determine the relative direction of the object from WCD 100. Theinformation received by both devices may be synchronized, for example,by control and DoA timing information sent from BTLEE receiver 720 toDoA receiver 703. Further, both receiving devices may then forwardinformation to central processor 300 which may combine, process, andformat the information for display on WCD 100. Although FIG. 7 shows tworeceivers 720 and 730, alternate embodiments of the invention can havemore than two receivers.

FIG. 7 also discloses two exemplary antenna configurations usable in atleast one embodiment of the present invention. The antennaconfigurations 700 and 710 may be implemented to improve signalreception and directional indication in the device. The more appropriateantenna configuration will depend on a variety of factors including thesize of the device, the composition (e.g., materials, layout,complexity, etc.) of the device, the antenna radiation characteristicsrequired for each antenna, antenna spacing, etc.

IV. The Directional Signal.

FIG. 8 discloses the makeup of an exemplary position-indicatingtransmission and different types of position indicating signals. Signaldescription 800 includes an example frame from a BTLEE/BluLitetransmission. While BTLEE/BluLite is used for this example, any of theaforementioned communication mediums may also be applicable. Initially,the transmission must be identified as a position-indicatingtransmission. The 16 bit preamble may include a code (e.g.,1010101010101010) that is used to indicate the beginning of the packetand to synchronize the receiver. This indication allows WCD 100 to beginmeasurement so that when the 8 bit service field is transmission, one orboth of the preamble and the service field may be measured by antennasA1-A6 in WCD 100. The transmission 800 may also include identificationinformation for the position-indicating transmission device, or otherdevice target related information as will be described below.

In addition, different types of position-indicating transmissionstrategies as disclosed in FIG. 8. Remotely activated locationtransmission 802 may be employed by a target whose signal emitter 500may be limited by low power concerns. These devices, such asbattery-operated transmitters in a keychain, in a wallet, embedded in anID badge, mounted in a vehicle such as an automobile, motorcycle,scooter, bicycle or in a piece of clothing, may be activated remotely bya user as needed. For example, the device may operate in a lower poweror power conservation mode until a message is received instructing adevice to activate the position-indicating transmission signal. Thismessage may be received by any of the aforementioned wireless mediumssuch as via a Bluetooth™ message. Alternatively, signal emitter 500 mayinclude a transponder, activated by a scanning signal from WCD 100. Thisscanning signal may be, for example, a UHF RFID signal. This signal mayactivate a transponder in a 5-10 meter range, and the transponder mayrespond with a signal that can be used to determine the object'srelative position, or may in turn trigger another subsystem in signalemitter 500 to transmit the position-indicating transmission.

In 804, the relative direction towards devices that require a request toactivate may be determined. These are typically powered devices that arein the possession of another user. For example, User 110 may want tolocate a friend that user 110 believes to be in the immediate area. User110 may send a message to the friend's WCD requesting an activation of aposition-indicating transmission. This message may occur via any of thelong-range mediums (for example, via SMS) or any of the short-rangemediums previously discussed. Depending on whether the friend isfamiliar with user 110, or for other security-related reasons, thefriend may accept or deny the request to activate theposition-indicating feature in their WCD. If the friend declines, amessage is returned to WCD 100 that indicates the friend has refused thelocating request. Alternatively, the friend may accept the request,activate their location beacon and WCD 100 may receive theposition-indicating transmission. This feature may be utilized forcommercial features as well. WCD 100 may indicate that there is a taxicab in the immediate area. User 110 may send a message to the taxirequesting to hire the cab and position indication. If the taxi isalready hired or on a break, the driver may refuse the request, orignore it. On the other hand, if the driver is looking for a fare he mayaccept the request, the relative position of the taxi being displayed inWCD 100 with other relevant information such as fare information.

A third type of target includes an always active position-indicatingtransmission 806. These signal emitters may be expanded range externallypowered devices, for example, Bluetooth™ access points. WCD 100 maydisplay these position markers so that user 110 may locate desiredservices. For example, a police car may include an always activeposition-indicator so that pedestrians may find them in times ofemergency. This same example may also apply to Hospital emergency rooms.In non-emergency situations, these always-on devices 806 may indicatewireless access points wherein a user may connect to the Internet via ashort-range wireless connection. Landmarks, commuter transportation suchas buses and trains, retail establishments (restaurants and stores) andentertainment venues may also utilize always-on position-indicatingtransmission emitters to advertise their services. More specificapplications for the use of always-on devices 804 will be discussedbelow.

FIG. 9 includes several flowcharts describing the process of operationfor at least one embodiment of the present invention. In step 900, user100 desires to find the location of a target. The user then activates aseeker application utilized to determine the relative direction towardsa target. In step 920, potential targets are displayed, and theposition-indicating transmission (locator beacon) of a desired targetmay be activated if necessary.

The determination of whether a locator signal requires activation instep 920 is detailed in steps 922-938. User 110 may first determinewhether a position-indicating transmission from a desired target hasbeen detected by WCD 100. This may entail user 110 viewing a list ofpotential targets discovered within effective transmission range of WCD100. Effective transmission range may be dictated by the wireless mediumin use. If the medium is, for example, Bluetooth™, the distance may beup to 100 meters. User 110 determines if the desired target is alreadyactive in step 924 by checking for its presence in the listing of targetdevices. If the device is active, then user 110 may select the deviceand WCD 100 may determine relative direction towards the device in step926. Alternatively, in step 928 an inactive device is subject to furtherdetermination as to whether the target device is configured to allowremote activation of its position-indicating transmission system. If thetarget device is configured to allow remote activation, then in step 930an activation message is sent to the target device via any of theaforementioned methods of wireless communication. Once WCD 100recognizes the signal, the target should then appear in the displayedtarget listing. User 110 may then select the target and WCD 100 maydetermine relative direction towards the device in step 926. Even if thetarget does not permit remote activation, it may be possible for user110 to request that the owner or controller of the target activate thelocator beacon. In step 932 a determination is made as to whether thepermissive activation of the target position-indicating transmission isavailable. If this feature is not available, then the location of thetarget may not be currently available (step 938). On the other hand, ifthis feature is available then a message is sent to the owner orcontroller of the target in step 934 requesting the starting of theposition-indicating transmission. The owner may either accept or refusethe request, the acceptance manifesting in the activation of the locatorbeacon, and the appearance of the target in the listing displayed on WCD100. User 110 may then select the device and WCD 100 may determinerelative direction towards the target in step 926. If the request isrefused, then the location of the target may not be currently available(step 938). Alternately, the request can be to change the transmittedsignal properties (e.g. packet repetition rate) to improve the DoAdetermination possibilities. For example, a position marker can be inpark mode where it's only transmitting one packet per second. Afterreceiving the activation request, it starts transmitting packets moreoften to speed up the direction finding.

In step 940 the position-indicating transmission is received by WCD 100on any of the antennas A1-A6. Steps 942-946 further describe thisprocess. Initially, in step 942 a transmission is received including apreamble that WCD 100 may recognize as a position-indicatingtransmission. Additional information may be decoded from this signalincluding information identifying the transmitting target, informationmonitored to determine DoA (such as the 8 bit service field) and anyother target relevant information (step 944). The received informationis the processed (step 946), and both the content related informationand the directional information may be used to provide information touser 110. Both the content related information including information oftarget identity and the directional information may be encrypted so thatit is available only to authorized devices that have the means to decodeit. The encryption is especially important in the case of always-onposition-indicating transmission emitters.

In step 960 the processed information may be displayed for user 110.This information may indicate the name of the target and the relativedirection towards the target from the current position of WCD 100.Further, the received information may include additional informationrelevant to the target. This information may be made available if user110 selects the target from the listing displayed on WCD 100. Thepossible content of the additional information will be discussed below.Further, information received from the various potential target devicesdiscovered in the effective transmission range of WCD 100 may be used totriangulate the approximate position of WCD 100 in absolute (e.g.,latitude and longitude) or relative (e.g., 150 meters North from target)terms.

V. An Exemplary Application for Direction Determination within aStructure

The present invention has numerous practical applications. In at leastone embodiment of the present invention, a system for determining bothcurrent position and relative direction to a target within a buildingstructure is disclosed.

FIG. 10 includes a building floor plan 1000. This floor plan isexemplary of any building floor plan in a high rise office building,government facility, educational facility, etc. A guest to building 1000may not be aware of the location of important landmarks within thebuilding. For example, visitors within the building may not know whererestrooms, meeting rooms, the main reception area, elevators, garagesand most importantly emergency exits reside. Further, visitors may notknow where certain contact people may be found. Presently a visitor mustrely on a combination of signage and their memory to determine theirway. However, in a large facility with many areas that look similar,this may still result in the guests or visitors becoming lost.

The present invention may aid to resolve this issue. A building mayinclude various position markers 1010 that transmit position indicatinginformation via short-range communication. Position marker 1010 may useany of the previously indicated short range communication technologiesin order to both transmission its identity and provide for DoAdetermination of relative direction and/or position. For example, user110 may be a visitor in a large commercial complex. User 110 may knowsome relevant information like the name of the conference room where ameeting is being held, the name of the person with whom user 110 isscheduled to meet, etc. Initially, user 110 may activate a seekerapplication on WCD 100 to aid in the determination of available targets(position markers 1010) in building 1000. In some cases, the presence ofWCD 100 inside the building may prompt the seeker program to wirelesslydownload a schematic of the building. This information may be availablevia a wireless access point using a communication medium likeBluetooth™, WLAN, GPRS, etc. The seeker program may use this buildingschematic in the direction and position location of various selectedtargets. Otherwise, the seeker application may simply indicate thecorrect direction to follow, such as with the pointer arrow displaypreviously described. To prevent unauthorized access to location orservice related information e.g. for security or business reasons, theinformation transmitted by the position markers 1010 may be encrypted sothat only such WCDs 100 that have the required key are able to accessthe information.

If user 110 initially selects “restrooms”, WCD 100 may indicate therelative direction to the closest restroom. Afterwards, user 110 mayselect the conference room or the individual with whom they are to meetto determine the relative direction to that individual. Further,selecting the target may give additional information about thatparticular target. For example, in the case of the conference room as atarget, WCD 100 may obtain additional information on the floor locationof a conference room, the name of the employee currently reserving theconference room, the schedule of use for the conference room, themaximum occupancy of the conference room, the presentation equipmentavailable in the conference room, etc. In the case of an individual, theperson may have a signal emitter 500 installed at their desk and/or havea low-power signal emitter on their person (e.g., embedded in anidentification badge). Information related to a person may include, theperson's name, position, office location and possibly a message foranyone who is looking for the person (e.g., “I am sick today,” “I'mtraveling on business,” “I'm on vacation,” “I'm in a meeting,” etc.).

In addition, certain device modes may be automatically triggered in WCD100. If, for example, a fire alarm is activated in the building, atransmitted transmission signal may automatically trigger the seekerprogram in WCD 100 to activate, select the nearest detected fire exit(marked by position marker 1010) and indicate the direction towards thisexit. In addition, general information may be provided with this signalinstructing user 110 regarding how to remain safe during the emergency.

FIG. 11 discloses an example of location determination in a buildingnavigation system. User 110 may implement a seeker program to indicateboth relative direction towards a target and the current position of WCD100. The current position of WCD 100 may be approximated, for example,through the triangulation of location relative to at least threeposition markers 1010. FIG. 11 shows user 110 and the location of user110 approximated in relation to three position markers 1010. Thislocation may be provided in relative terms, for example, that user 110is a certain distance from a particular position marker, or that theuser is in a certain hallway, on a certain floor, in a certain wing,etc. These features may be used in conjunction with a building schematicdownloaded to WCD 100 as described above.

FIG. 12 discloses a process flowchart in accordance with at least oneembodiment of the present invention. In step 1200 the user may activatea seeker program to scan the premises for targets that are currentlyemitting a position-indicating transmission. An optional step 1204 mayprovide for downloading a building schematic via wireless communication,if such information is to be made available to WCD 100. As a furthersecurity option in step 1208, only if the WCD 100 is authorized, can thediscovered position markers 1010 in the building schematic be listed onWCD 100, as provided in step 1210. The authorization in step 1208 can beimplemented by encoding the downloaded information so that it is onlyuseable by the receiving WCD 100 if it is authorized, for example, by apre-stored authorization program. WCD 100 may also estimate its currentposition by sensing at least three position markers 1010, and using thisinformation in a triangulation process in step 1220. This approximateposition information may also be displayed on WCD 100. User 110 may thenselect from among the discovered position markers 1010 indicated on WCD100 (step 1230), and WCD 100 may indicate the relative direction towardsthe position marker from its current position.

VI. An Exemplary Application for Direction Determination in an OutdoorsEnvironment

The present invention is also readily applicable to outside directionand position determination. FIG. 13 presents an example. In thisscenario, user 110 enters a locality wherein position markers reside1010 (similar to FIG. 10). However, these targets are installed atvarious locations throughout the area to provide direction finding tovarious service providers and locations of public interest.

FIG. 13. discloses examples of position markers that may reside in anoutdoors location finding system. These position markers may be placednear locations or items that user 110 may desire to find, and mayinclude an extended range always-on type position-indicatingtransmission emitter since these units may be hardwired to an externalpower source. The position markers may include absolute positionalcoordinates, such as the longitude and latitude of each positionalmarker. This information may be used to estimate the actual position ofuser 110 via triangulation. The current position may be updated as user110 moves throughout the area.

For example, public transportation like a bus or train station mayinclude a position marker. User 110 may activate a seeker applicationthat goes out and gathers information on all available targets withintransmission range. This display may be periodically updated as a usertravels throughout the area. When a user selects the bus or trainstation on the display of WCD 100, additional information relevant tothese locations may be viewed such as the address location of thestation or stop, commuter fairs, schedules, the arrival time of the nextbus/train, delay alerts, etc Likewise, other information may beavailable for other types of position indicators. The informationtransmitted by the position markers may be encrypted to restrict theaccess to authorized devices only.

Retail establishments are another example of an entity that mayimplement position indication through position markers 1010. FIG. 13includes examples of a restaurant and a flower shop, but the inventionis in no way limited to these types of stores. The restaurant “Luigi's”may provide additional information (besides location information)regarding menu items or a daily special. This information may be usefulto user 110 in determining whether to patronize this diningestablishment Likewise, the Flower shop may send additional informationthat includes items that may be currently discounted as part of a sale.This information is a component of the position-indicating transmission,and is made available on WCD 100 when the user selects to see moreinformation concerning position marker 1010.

Event information may also be available to user 110 via the exemplaryoutdoor location system. WCD 100 may receive location-indicatingtransmissions from position markers at a cinema, theatre, arena, etc.The transmission may also include an event schedule, movie show timesand ticket prices for various productions. User 110 need only selectthis position marker on WCD 100 to have WCD 100 indicate the relativedirection to position marker 1010 from its current location.

Emergency services may be indicated automatically in the case of ageneral emergency, or may be selected by user 110 in the case of apersonal emergency, accident, etc. The automatic activation of a seekerapplication and direction indication to a particular position marker1010 in a general emergency may be triggered by a long-range orshort-range transmission signal from a disaster management agency.Position markers 1010 may be installed in a stationary location, such asa hospital emergency room, or in a moving object such as a police car.An advantage of the present invention is that it can display bothrelative and absolute position, allowing for the tracking of a movingobject. The ability to track the current location of the closest policevehicle relative to a current location could be essential in alife-threatening situation. Position markers 1010 for emergency servicesmay further contain location-related information and instructioninformation regarding procedure for a given emergency (fire, seriousweather, tenor attacks, etc.)

FIG. 14 discloses an exemplary process flow in accordance with thesystem of FIG. 13. In step 1400 user 110 activates a seeker applicationon WCD 100 to scan the immediate area for potential targets. After thelist of potential targets is compiled and displayed (step 1410), user110 may select any of the position markers 1010 to determine if thesetargets have additional information included relevant to the location“sponsoring” the target. The additional information will be displayed tothe user in step 1430 if it was included in the position-indicatingtransmission. Otherwise, the system proceeds to step 1440, wherein thecurrent location of WCD 100 may be approximated, for example, viatriangulation determined from at least three sensed position markers. Instep 1450, user 110 selects from among the indicated position markers1010 to indicate to WCD 100 the target to which the relative directionis sought. WCD 100 responds in step 1460 by monitoring and processingthe position-indicating transmission from the selected position markerand indicating the relative direction towards that position marker.

FIG. 15 illustrates triangulation based on angles. The coordinates(x₁,y₁), (x₂,y₂), and (x₃,y₃) of the position markers (PM1, PM2, PM3)are known a priori. α₁₂, α₂₃, and α₁₃ are measured. Then location of theWCD 100 (x,y) can be calculated. Only two position marker directionsneed to be measured if the device has a compass. In addition to locationthe invention can solve the orientation of the device. The orientationcan be solved in relative terms and also in the geographical coordinatesystem (relative to North), provided that the latitude and longitude ofthe position markers is known.

In addition to finding services based on signals received directly fromposition markers located at the service location, other aspects of theinvention include the following implementations:

-   -   The user can get information also about services, which are        currently outside the operational range of the system. This is        carried out in at least three ways:

1. The position markers broadcast information not only about themselves,but also about other close-by services, whose position markers are stilltoo far away for their signals to be received by the device. Also thelocal map/building floor plan information can be transmitted, includingthe position marker positions.

2. The device downloads information of services in a certain area, aswell as the local map/building floor plan, plus the position markerlocations, e.g. through GPRS, WLAN, or some other connection from aremote database. The information may contain locations and otherinformation of potential targets that are moving, such as taxis andbuses. This information may originate from the GPS system or some otherlocation system.

3. Information of any fixed services and other potential targets, aswell as maps and building floor plans may also reside locally within theuser device.

-   -   After selecting a service or location from the list or from the        map, and using the location and orientation determining        capability offered by the position markers between the current        user location and the target location, the user is able to        receive navigation instructions towards any service location in        the area (known by the user by e.g. either of the three means        mentioned above), including those that would be currently out of        the operational range of the direction finding system.    -   The navigation instructions are given e.g. by showing a map or        floor plan (oriented according to the real orientation of the        user) and by pointer arrows showing the directions in which the        user should proceed to reach the desired destination.    -   When arriving close to the target, the user is guided directly        to the target by using a position marker located at the target,        provided that the target is equipped with a position marker.

The present invention provides an improvement over current locationsystems due to its ability to satisfy a multitude of requirements for auser. The present invention allows a user to find both locations andobjects. Personal objects may be located within a short transmissionrange if the object includes a low power position-indicatingtransmission emitter. In some cases these signal emitters may beactivated via a wireless message or a transponder signal. Further, awireless communication device owned or controlled by another user may belocated after permission is requested via a wireless message. Thepresent invention also allows a user to find places, regardless ofwhether these locations are currently known or unknown to a user. Theuser may select from a list of all potential targets found in a givenarea, and may view information on each of these targets received as partof the position indicating signal. Since, according to at least oneembodiment of the present invention, a wireless communication device mayshow both relative and absolute position, moving targets may be tracked.In another beneficial application, emergency situations mayautomatically trigger a wireless communication device to indicate aroute to safety. All of these combined features may be implemented usingembodiments of the present invention, which enables the determination ofboth direction towards a selected target and the current position of aseeking device, both inside and outside a structure. As a result, thepresent invention exceeds the current abilities of known locationdetermination systems.

Accordingly, it will be apparent to persons skilled in the relevant artthat various changes in forma and detail can be made therein withoutdeparting from the spirit and scope of the invention. The breadth andscope of the present invention should not be limited by any of theabove-described exemplary embodiments, but should be defined only inaccordance with the following claims and their equivalents.

1. A device, comprising: an antenna array comprising a plurality ofantennas; a switching device, coupled to at least the antenna array,configured to select each of the plurality of antennas in the antennaarray; a receiver, coupled to at least the switching device, configuredto receive signal information from the antenna array; and a controllerconfigured to determine source identification information based on thereceived signal information; and a display configured to display a listof targets based on the source identification information, wherein thecontroller is further configured to determine a relative directiontowards one of the displayed targets by calculating a direction ofarrival estimation based on the received signal information, and todisplay the relative direction on the display.
 2. The device of claim 1,wherein the antenna array is incorporated within the device.
 3. Thedevice of claim 1, wherein the antenna array is externally attachable tothe device in a predetermined orientation.
 4. The device of claim 1,wherein the switching device switches between the plurality of antennasin the antenna array in rapid progression.
 5. The device of claim 1,wherein the switching device sequentially feeds signal information fromantennas in the antenna array to the receiver, for processing the signalinformation by the controller to determine a relative direction to atarget.
 6. The device of claim 1, wherein the receiver comprises two ormore receivers including a receiver for receiving the sourceidentification information and another receiver for processing thedirection of arrival estimation based on the received signalinformation.
 7. The device of claim 6, wherein the two or more receiversfurther comprise a receiver for processing communication informationconveyed within the received signal information.
 8. The device of claim1, wherein the device is a wireless communication device capable of atleast one of long-range, short-range and near-field communications. 9.The device of claim 8, wherein the signal information is a communicationsignal capable of conveying communication information to and from thedevice.
 10. The device of claim 9, wherein the communication informationcomprises at least one of audio information and video information. 11.The device of claim 1, further comprising a UHF RFID scanner configuredto trigger the activation of a signal in a target by scanning thetarget.
 12. A method, comprising: receiving wireless signals fromposition markers into a device; receiving schematic information viawireless communication into the device; displaying a list of positionmarkers from which the wireless signals were received on the device;selecting, on the device, a position marker from the list of positionmarkers; and indicating, on the device, the relative direction towardsthe selected position marker, with respect to the schematic information,from the current position of the device.
 13. The method of claim 12,wherein the position markers are located within a building and theschematic information pertains to the interior of the building.
 14. Themethod of claim 12, wherein selecting a position marker results ininformation related to the selected position marker being displayed onthe searching device.
 15. A computer program product comprising computerexecutable program code recorded on a computer readable storage medium,the computer executable program code comprising: code configured tocause a device to receive wireless signals from position markers; codeconfigured to cause the device to receive schematic information viawireless communication; code configured to cause the device to display alist of position markers from which the wireless signals were received;code configured to allow for selection, on the device, of a positionmarker from the list of position markers; and code configured to causethe device to indicate the relative direction towards the selectedposition marker, with respect to the schematic information, from thecurrent position of the device.
 16. The computer program product ofclaim 15, wherein the position markers are located within a building andthe schematic information pertains to the interior of the building. 17.The computer program product of claim 15, wherein selecting a positionmarker results in information related to the selected position markerbeing displayed on the device.
 18. A system comprising: a devicecomprising an antenna array including a plurality of antennas; positionmarkers located within a building; the device receiving wireless signalsinto the antenna array from the position markers and further receivingschematic information pertaining to the inside of the building viawireless communication; the device further displaying a list of theposition markers and providing the ability to select a position markerfrom the list of position markers; and the device further indicating therelative direction towards the selected position marker, with respect tothe inside of the building as described by the schematic information,from the current position of the device.